Electrical switch with kinetic energy dissipating means



S. H. KAST May 13, 1947.

ELECTRICAL SWITCH WITH KINETIC ENERGY DISSIPATING MEANS 2 Sheets- Sheet1 Filed Aug. 5, 1942 GKOUND/NG 3 WITCH 1 0 5 CONNECT SW/ TCH May 13,1947. s. H. KAST 2,420,485

ELECTRICAL SWITCH WITH KINETIC ENERGY DISSIPATING MEANS Filed Aug. 5,1942 2 Sheets-Sheet 2 ii j: a

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Patented May 13, 1947 UNITED" STATES PATENT OFFI ELECTRICALSWITCHW'ITH'KINETIC ENERGY DISSIPATING MEANS Samuel H-. Kast;Greensburg. Pa., assignor to Railway and Industrial Engineeringpompany,Greensburg, 1a., a corporation of Delaware Application August 5, 1942-;Serial No-4'53;711

Claims. 1

This invention relates to electrical switches and to constructions thatare appropriate for use-in disconnect switches but that areparticularly'use ful in grounding switchesthat are closedautomaticallyby heavy springs ina time interval of the order of 8 to 10 cycles on a60 cycles per second distribution circuit.

The switch blade must be of relatively light weight topermit rapidacceleration whenthe operating. mechanism is tripped; and the kineticenergy of the rapidly-moving rblade can best be absorbed bycontactelements that engage *under appreciable pressure tobringthe blade to --aslid ing stopi Th'eopening movement of the blade must overcome-thefriction of the blade onthe jawi element but it is possible toreduce-this frictional resistance of'the contact membersduring theopening of the blade.

An object of this invention is to provide an electrical switch in whichthe blade contact hasa relatively long travel within aresilient jawcontact whose opposed contact elements establish a substantial pressureupon the blade contact; thereby dissipatingthe-kinetic energy of themoving blade and establishing a contact engagement of low resistance,the blade contact being of suchdesign that itcollapses upon an openingmovement of the "switch blade to reduce or eliminate the pressureexerted on-the movable contact by the jaw contact. An objectisto providea switch including a blade contact of two sections pivotally connectedto form a toggle that is spread during a closing-movement of the switchblade to establish a high pressure engagement with the opposed contactelements of a jaw contact, and is collapsed upon an opening movement ofthe blade to relieve the contact pressure and the frictional resistanceto movement of the switch blade. Another object is to provide aswitchjaw contactincluding opposed contact elements of relatively greatlength, as measured along the path of move ment'of the bladecontact,-that are pivotally connected and'spring pressed-towards each othertoexert upon amovable blade contact a pressure that is substantially:independent of the position of the blade contact within the jaw contact.More specifically, anobject is to provide a jaw contact of the typestated in which the elongated contact elementsof the jaw contact arepivotall-y connected forangular movement about an axis or axessubstantially parallel to the pathof movement of the blade'contact asitmoves into the jaw contact.

These' an'd' otheriobjects" and advantages of the invention' willbe-apparent from the following 2.. specification when-taken with theaccompanying; drawings in'which:

Fig; 1 is-a fragmentary front elevation of a grounding :switch embodyingthe invention;

Fig. 2 is a fragmentary top planview of the switch; with the switchblade shown in position approaching, but outside of, the jaw contact;

Fig. 3 -is aside elevation of the jaw contact;

Fig; 4 is a fragmentaryperspective view of the contact end of the blade;and

Figs- 5 and-6 are end views of the-contact blade showing; the contactmembers in spread and in collapsed positions, respectively.

In the drawings, the reference numeral identifies a-stationaryinsulating column that supports the-base 2 of the hinge terminal of adisconnect switch 3 that is to be grounded by the switch that embodiesthe present invention. I-he jawcontact of thegrounding switch is mountedupon the terminal base '2, and the blade 4 of the grounding switch issupported upon an operating. shaft 5 that is journalledupon thesteelframework 6 on which the insulator column I is mounted.

The operating shaft 5' is preferably actuated by a strong spring, notshown, that accelerates the blade 4 rapidly to effects, quick closure ofthe groundingrswitch, Whether operated by a strong springor manually;the blade 4 is moving rapidly asit reaches the contact jaw, and itskinetic energymust-be dissipatedat a relatively slow rate to-avoidexcessive stresses in the-blade 4.- The kinetic energy is dissipated bya relatively long travel of the switch blade within the jaw againstafrictional resistance that is substantially constant over the entirerange of movement of the blade within the jaw.

The switch'jawcomprises a yoke or U-shaped base i thatis-bolted to thedisconnect switch base 2, and'apair of opposed contact elements- 8, 8'that-are pivotallysupported upon the base I on shafts 9 that aresubstantially parallel to a tan ent :to the arcuate-path of-movement ofthe contact end of the blade as it enters the switchjaw: The elongatedcontact surfaces 8' of the contact elements 8 are-substantially parallelto eachotherand to the shafts 9, and-areurged toward each other by apair of springs l0= that are supported on and between flanges ll of thecontact elements. The springs are seatedin recesses inone of the flangesl l and are-mounted on shouldered studsi 2-that-are threaded intotheother flange ll 'foradjustment to determine the pressure exerted uponthe switch blade by'the jaw-contact elements. A bolt I3- extends throughthe flanges H and carries a nut [4 that may be turned down upon the boltto determine the minimum width of the contact jaw when the groundingswitch is open. Flexible current-carrying jumpers [5 are connectedbetween lugs IS on the contact elements 8 and the jaw base I, thejumpers being preferably fitted over the shafts 9 and clamped to thebase 1 by nuts I! that are threaded upon shafts 9. A rubber stop I8 issupported below the contact surfaces 8 by an inverted T-shaped member [9that is secured to the base I but, in normal operation, the blade 4 willbe arrested by frictional resistance before it reaches the stop [8.

The contact means of the switch blade 4 has a normal width somewhat inexcess of the spacing of the jaw contact surfaces 8' when the switch isopen, and the springs It! therefore establish a high pressure contactengagement that provides the frictional resistance for arresting therapidly moving switch blade and affords a high pressure contactengagement of low electrical resistance. The blade contact meanscomprises a pair of laterally alined contact members 20 that arepivotally mounted on the reduced diameter end 2| of the blade 4 forrocking movement about the axes of the blade. Torsion springs 22 areconnected between the contact members 20 and flanges 23 on the blade 4to urge the contact members in opposite directions to engage the arcuatestop 24 that positions the contact members in diametrical alinementcorresponding to a maximum width of the blade contact means.

The frictional resistance to movement of the blade into the resilientcontact jaw establishes forces on the contact members 20 that act in thesame sense as the springs 22 to hold the contact members in spread ormaximum width position. The frictional resistance operates in oppositionto the springs 22 upon an opening movement of the switch, and thesprings 22 yield to permit a rocking movement of the contact members toreduce the pressure exerted upon the blade contact members by thecontact jaw elements, thereby reducing the frictional resistance to anopening movement of the switch.

The switch blade assembly is of relatively light weight and can beclosed quickly by a spring mechanism, not shown, and the high speedmovement is gradually slowed down by friction between the jaw contactelements 8 and the blade contact members 20. This frictional resistancemay be substantially constant over the full range of movement of theblade within the jaw, but it can be increased or decreased with themovement of the blade contacts by appropriate design of the contactsurfaces 8' of the jaw contact elements. The frictional resistance issubstantially reduced upon an opening movement of the switch by therocking of the blade contact members in opposition to the forces exertedby the springs 22.

A preferred embodiment of the invention has been illustrated anddescribed but it is to be understood that the invention is not limitedto automatic grounding switches and that various changes may be madewithin the spirit of my invention as set forth in the following claims.

I claim:

1. In an electrical switch, a blade pivotally supported for angularmovement in opposite directions for switch closing and switch openingmovements respectively, contact means at the outer end of the blade, ajaw contact for engagement by said blade contact means and includingopposed relatively movable contact elements having elongated contactsurfaces substantially parallel to each other and to a line parallel tothe arcuate path of the blade contact means as it enters the jawcontact, elongated pivot means supporting at least one of said contactelements for rocking movement about an axis parallel to said contactsurfaces, spring means urging said contact elements towards each otherto exert a substantial pressure upon the blade contact means as it movesinto and along the jaw contact, and means limiting the relative rockingmovement of said contact elements to determine the minimum spacing ofsaid contact surfaces upon movement of blade contact means out of thejaw contact.

2. In an electrical switch, the invention as claimed in claim 1, whereinsaid jaw contact includes a base member and said elongated pivot meanssupports each of said contact elements on said base member for rockingmovement about spaced axes each parallel to said contact surfaces.

3. In an electrical switch, the invention as claimed in claim 1, whereinsaid jaw contact includes a base member and said elongated pivot meanssupports each of said contact elements on said base member for rockingmovement about spaced axes each parallel to said contact surfaces, andsaid spring means is supported on and between said contact elements toexert pressure thereon to urge the blade-engagin contact surfaces ofsaid contact elements towards each other.

4. In an electrical switch, the invention as recited in claim 1, whereinsaid blade contact means include contact members supported on said bladefor relative movement, under the frictional drag exerted on said contactmembers by the springpressed contact elements during a switch openingmovement of said blade, to decrease the eifective width of the bladecontact means, thereby automatically to reduce the frictional resistanceto movement of the blade contact means out of said jaw contact to avalue substantially lower than that of the frictional resistance tomovement of the blade contact means into and along the jaw contact.

5. In an electrical switch, a jaw contact including opposed andrelatively elongated contact elements resiliently pressed towards eachother, a switch blade and means supporting the same for angular movementin opposite directions to carr the contact end thereof into and out ofsaid jaw contact, and contact means on said blade for engagement withsaid contact jaws; said contact means including a contact member pivotedupon said blade for angular movement about the axis thereof and movableto vary the effective width of the contact means, and spring meansurging said contact member into position to present a maximum width ofsaid contact means for wedging engagement with said contact jaw.

6. In an electrical switch, the invention as recited in claim 5, whereinsaid spring means exerts a force on said contact member lessthan thatarising from the frictional resistance to movement of the contact meansout of said contact jaw upon an opening movement of the switch blade,whereby said contact is automatically rocked to reduce the frictionalresistance to movement upon switch opening movement of the switch blade.

'7. In an electrical switch, the invention as recited in claim 5,wherein said contact means comprises two contact members alinedtransversely of the switch blade and pivoted thereon for rockingmovement about the axis of the blade, and said spring means exertsforces upon said contact members in the same sense as that of the forcesdeveloped upon said contact members by the frictional resistance tomovement of said contact members into said contact jaw.

8. A switch jaw for cooperation with a pivotally mounted switch bladeand comprising a base, a pair of contact elements, each contact elementhaving an elongated contact surface substantially parallel to a tangentto the arcuate path of movement of a switch blade as it enters theswitch jaw, elongated shafts pivotally mounting said contact elementsupon said base for rocking movement about axes substantially parallel tothe associated contact surface, and spring means urging said contactsurfaces towards each other.

9. A switch jaw as recited in claim 8, wherein said contact elementseach includes a flange extending to the side of their respectivesupporting shafts opposite their elongated contact surfaces, and saidspring means comprises compression springs supported between saidflanges of the contact elements.

10. A switch jaw as recited in claim 8, wherein said contact elementseach includes a flange extending to the side of their respectivesupporting shafts opposite their elongated contact surfaces, and saidspring means comprises compression springs supported between saidflanges of the contact elements, in combination with a bolt extendingthrough said flanges to limit the minimum spacing of said elongatedcontact surfaces SAMUEL H. KAST.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,095,554 Maseng Oct. 12, 1937888,760 Smythe May 26, 1908 1,935,597 Koppitz Nov. 14, 1933 792,860Sundh June 20, 1905 856,737 Sill June 11, 1907 2,254,914 Rugg Sept. 2,1941 638,036 White Nov. 28, 1899 615,665 Guett Dec. 6, 1898 2,309,909Koppitz Feb. 2, 1943 2,306,117 Dunlap Dec. 22, 1942 964,037 Lux July 12,1910 981,452 McNally Jan. 10, 1911 FOREIGN PATENTS Number Country Date603,820 Germany Oct. 9, 1934 378,567 Great Britain 1932

